Messages in this thread | | | Date | Thu, 19 Jul 2018 14:47:40 -0400 | From | Johannes Weiner <> | Subject | Re: [PATCH 08/10] psi: pressure stall information for CPU, memory, and IO |
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On Wed, Jul 18, 2018 at 02:03:18PM +0200, Peter Zijlstra wrote: > On Thu, Jul 12, 2018 at 01:29:40PM -0400, Johannes Weiner wrote: > > + /* Update task counts according to the set/clear bitmasks */ > > + for (to = 0; (bo = ffs(clear)); to += bo, clear >>= bo) { > > + int idx = to + (bo - 1); > > + > > + if (tasks[idx] == 0 && !psi_bug) { > > + printk_deferred(KERN_ERR "psi: task underflow! cpu=%d idx=%d tasks=[%u %u %u] clear=%x set=%x\n", > > + cpu, idx, tasks[0], tasks[1], tasks[2], > > + clear, set); > > + psi_bug = 1; > > + } > > WARN_ONCE(!tasks[idx], ...);
It's just open-coded because of the printk_deferred, since this is inside the scheduler.
It actually used to be a straight-up WARN_ONCE() in older versions. Recursive scheduling bugs are no fun to debug ;)
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